Alright, Ive been looking at turbos lately, and it looks like external wastegates are the way to go with
any turbo. The main problem isn't odd surfaces or a flow bottleneck or anything like that, but the pressure and/or flow rate difference between the wastegate and turbine. Plumb an external wastegate in to your downpipe and you'll see the same losses. So... The internal wastegate isn't the problem, just the fact that, by nature, it's going to be stuck flowing in to the same downpipe as the turbine.
Enter the Mitsubishi 16G. Just like what we upgrade to on Subarus, but 1) different flanges, 2) cheaper and easier to come by and 3) there's a wall between the wastegate and turbine.
On the Eclipses, they apparently have an "o2 housing" which is basically a bellmouth where the o2 sensor sits, and then bolts up to a single downpipe. Good for them. I want to put a dump tube right there instead. Thoughts?
Why? External wastegates are expensive and with this size of a turbo not necessary. Plus it's a
really tight fit -- there are a couple companies selling an up pipe with a flange for 38/44mm wastegates, but they're $400+
without the gate. For this setup, we could just get an HKS downpipe off ebay for $100ish and a pair of 16G exhaust flanges for under $50. Plus, and this probably isn't important for most of us, but if a straight dump tube is too loud, there's plenty of room around the downpipe to maybe put small (moped?) muffler or something to keep it quiet.
Edit: Witness my MS Paint skills.
